Retaining wall block

ABSTRACT

A retaining wall block has parallel top and bottom faces, a front face, a rear face, first and second side wall faces and a vertical plane of symmetry extending between the front and rear faces. The block is formed as a body portion including the front face, a head portion including the rear face and a neck portion connecting the body portion and the head portion. The body, head and neck portions each extend between the top and bottom faces and between the first and second side wall faces. An opening extends through the neck portion from the top face to the bottom face, dividing the neck portion into first and second neck wall members extending rearwardly from the body portion to the head portion.

This application is a continuation of application Ser. No. 13/007,828,filed Jan. 17, 2011, which is a continuation of application Ser. No.12/646,120, filed Dec. 23, 2009, now U.S. Pat. No. 7,871,223 B2, whichis a continuation of application Ser. No. 12/105,064, filed Apr. 17,2008, now U.S. Pat. No. 7,654,776 B2, which is a continuation ofapplication Ser. No. 11/698,341, filed Jan. 26, 2007, now U.S. Pat. No.7,448,830 B2, which is a continuation of application Ser. No.09/312,352, filed May 14, 1999, now U.S. Pat. No. 7,168,892 B1, thecontents of each of which are hereby incorporated herein by reference.

FIELD OF THE INVENTION

The present invention is directed to the field of retaining walls andblocks used to construct a retaining wall.

BACKGROUND TO THE INVENTION

Numerous methods and materials exist for the construction of retainingwalls. Such methods include the use of natural stone, poured in placeconcrete, masonry, and landscape timbers or railroad ties. In recentyears, segmental concrete retaining wall units which are dry stacked(i.e., built without the use of mortar) have become a widely acceptedproduct for the construction of retaining walls. Examples of suchproducts are described in U.S. Pat. No. Re. 34,314 (Forsberg '314) andU.S. Pat. No. 5,294,216 (Sievert). Such products have gained popularitybecause they are mass produced, and thus relatively inexpensive. Theyare structurally sound, easy and relatively inexpensive to install, andcouple the durability of concrete with the attractiveness of variousarchitectural finishes.

The retaining wall system described in Forsberg '314 has beenparticularly successful because of its use of block design thatincludes, among other design elements, a unique pinning system thatinterlocks and aligns the retaining wall units, allowing structuralstrength and efficient rates of installation. This system has also shownconsiderable advantages in the construction of larger walls whencombined with the use of geogrid tie-backs hooked over the pins, asdescribed in U.S. Pat. No. 4,914,876 (Forsberg).

The construction of modular concrete retaining walls as described inForsberg involves several relatively simple steps. First, a leveling padof dense base material or unreinforced concrete is placed, compacted andleveled. Second, the initial course of blocks is placed and leveled. Twopins are placed in each block into the pin holes. Third, core fillmaterial, such as crushed rock, is placed in the cores of the blocks andspaces between the blocks to encourage drainage and add mass to the wallstructure. Fourth, succeeding courses of the blocks are placed in a“running bond” pattern such that each block is placed between the twoblocks below it. This is done by placing the blocks so that thereceiving cavities of the bottom of the block fit over the pins thathave been placed in the units in the course below. As each course isplaced, pins are placed in the blocks, the blocks are corefilled withdrainage rock, and the area behind the course is backfilled andcompacted until the wall reaches the desired height.

If wall height or loading conditions require it, the wall structure maybe constructed using reinforced earth techniques such as geogridreinforcement, geosynthetic reinforcement, or the use of inextensiblematerials such as steel matrices. The use of geogrids are described inU.S. Pat. No. 4,914,876 (Forsberg). After placement of a course ofblocks to the desired height, the geogrid material is placed so that thepins in the block penetrate the apertures of the geogrid. The geogrid isthen laid back into the area behind the wall and put under tension bypulling back and staking the geogrid. Backfill is placed and compactedover the geogrid, and the construction sequence continues as describedabove until another layer of geogrid is called for in the planneddesign. The use of core fill in the blocks is known to enhance the wallsystem's resistance to pull out of the geogrid from the wall blocks whenplaced under pressure.

Existing segmental wall block designs have proven quite versatile, buthave limitations in constructing certain structures. A common designdetail for retaining wall structures is to include a fence or guardrailat the top of the retaining wall. Many segmental wall designs are notable to accommodate the anchoring posts for such structures. Similarly,it is not always feasible to extend geosynthetic reinforcement behind awall. This may occur due to the presence of a structure or a propertyline immediately behind the wall. Most existing modular walls blockscannot be constructed through the use of grout and rebar reinforcement.

There is a need for a retaining wall block that improves on the Forsbergdesign. Since the blocks are usually placed through manual labor, itwould be desirable to decrease the weight of the Forsberg design withoutcompromising the performance characteristics of the block. Because theplacement of corefill is an important factor influencing wallconstruction efficiency, it would be desirable to improve the ease withwhich core fill may be placed. It would also be desirable to improve theForsberg blocks' ability to resist pull out of geosyntheticreinforcement placed between courses of the blocks. It would also bedesirable to have a wall block design that would allow construction ofsuch common construction details as the placement of guardrail posts orfence posts at the top of the wall, or the provision of pilasters foraesthetic or other purposes. It would also be desirable to provide ablock that would allow the wall to be reinforced with rebar and concretegrout rather than soil reinforcement.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an improvedretaining wall block satisfying at least one of the above desires.

In one aspect the present invention is a retaining wall block havingparallel top and bottom faces, a front face, a rear face, first andsecond side wall faces and a vertical plane of symmetry extendingbetween the front and rear faces, the block comprising

a body portion including the front face,

a head portion including the rear face,

a neck portion connecting the body portion and the head portion, thebody, head and neck portions each extending between the top and bottomfaces and between the first and second side wall faces,

an opening extending through the neck portion from the top face to thebottom face, the opening dividing the neck portion into first and secondneck wall members extending rearwardly from the body portion to the headportion,

first and second pin holes each disposed in the body portion and openingonto the top face for receiving a pin with a free end of the pinprotruding beyond the top face,

first and second pin receiving cavities each disposed in the bodyportion and opening onto the bottom face for receiving the free end of apin received in a pin hole of an adjacent block disposed therebeneath soas to interlock the blocks with a predetermined setback,

wherein the neck wall members, the pin holes and the pin receivingcavities are positioned such that a first plane extending parallel tothe plane of symmetry passes through the first pin receiving cavity, thefirst pin hole and the first neck wall member and a second planeextending parallel to the plane of symmetry passes through the secondpin receiving cavity, the second pin hole and the second neck wallmember.

Typically the first and second neck wall members are each positioned soas to substantially vertically align, in use, with a the neck wallmember of a vertically adjacent block in an adjacent courses of a wallmade from a plurality of courses of the blocks laid in a running bondpattern.

Typically the first and second planes are located approximately midwaybetween the plane of symmetry and laterally outermost points of thefirst and second the wall faces, respectively.

Preferably the first and second pin receiving cavities each have a rearwall extending generally perpendicularly to the plane of symmetry.

Preferably the block further comprises third and fourth pin holes eachdisposed in the body portion and opening onto the top face for receivinga pin with a free end of the pin protruding beyond the top face, thethird and fourth pin holes being disposed on the first and second planesforward of the first and second pin holes so as to provide a reduced orzero predetermined setback.

Preferably the side wall faces generally taper from the front face tothe rear face.

Preferably the head portion has first and second ears extendinglaterally beyond the first and second neck wall members, respectively,the first and second ears each being provided with a notch to enable theears to be knocked off the head portion.

The present invention further provides a retaining wall formed of aplurality of courses of the blocks laid in a running bond pattern,blocks of a given course each having a pair of pins each projectingbeyond the top surface of the block and engaging the pin receivingcavity of a vertically adjacent block in the next lowermost course, acontinuous cavity being defined by each the opening of verticallyaligned blocks in every second course of the blocks communicating withside voids of vertically adjacent blocks in each alternate course, theside voids of a block being defined between the head and body portionseither side of the neck portion of the block.

The retaining wall may be a straight wall, a curved wall or a serpentinewall.

The retaining wall may be reinforced with rebar and grouting, a lengthof the rebar passing through each of at least one of the cavities, eachlength of the rebar being secured in the respective cavity with grout.

The retaining wall may incorporate at least one post each extending intoa the continuous cavity and protruding from the top course, each of theat least one post being secured in the respective cavity with grout.

The retaining wall may incorporate a geogrid tie-back disposed betweentwo adjacent the courses, the geogrid tie-back being secured with thepins passing through apertures thereof.

The retaining wall may incorporate a pilaster formed of a column of theblocks set forward from the remainder of the wall.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred form of the present invention will now be described by wayof example with reference to the accompanying drawings, wherein:

FIG. 1 is a plan view of a retaining wall block.

FIG. 2 is an inverse plan view of the retaining wall block of FIG. 1.

FIG. 3 is an isometric view from above and in front of the retainingwall block of FIG. 1.

FIG. 4 is an isometric view from below and behind of the retaining wallblock of FIG. 1.

FIG. 5 is a plan view of a three interlocked retaining wall blocks.

FIG. 6 is a plan view of an alternative retaining wall block.

FIG. 7 is an inverse plan view of the alternative retaining wall blockof FIG. 6.

FIG. 8 is a perspective view of a retaining wall built of the retainingwall block of FIG. 1.

FIG. 9 is a plan view of a section of the retaining wall of FIG. 8.

FIG. 10 is a front elevation view of a pin for use with a retaining wallblock.

FIG. 11 is a plan view of two retaining wall blocks laid in a tightconvex curve.

FIG. 12 is a plan view of the retaining wall blocks of FIG. 11 with athird block interlocked therewith.

FIG. 13 is a perspective view of a retaining wall similar to that ofFIG. 8 but reinforced with rebar and grout.

FIG. 14 is a perspective view of a retaining wall similar to that ofFIG. 8 but incorporating a geogrid tie-back and fence posts.

FIG. 15 is a plan view of a section of the retaining wall of FIG. 14.

FIG. 16 is a perspective view of a retaining wall similar to that ofFIG. 8 but incorporating a pilaster.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring to FIGS. 1 to 4 there is shown retaining wall block 1according to a preferred embodiment of the present invention. Block 1 ismade of a rugged, weather resistant material, preferably pre-castconcrete. Other suitable materials are plastic, reinforced fibers, wood,metal and stone. Block 1 has parallel top face 2 and bottom face 3,front face 4, rear face 5 and first and second side wall faces 6 and 7.Front face 4 and rear face 5 each extend from top face 2 to bottom face3 and side wall faces 6, 7 extend from top face 2 to bottom face 3 andfrom front face 4 to rear face 4. Block 1 is generally symmetrical aboutvertical plane of symmetry S.

The integrally formed block 1 takes the form of body portion 8, headportion 9 and neck portion 10 connecting body portion 8 and head portion9. Front face 4 forms part of body portion 8, while rear face 5 formspart of head portion 9. The body, head and neck portions 8, 9, and 10each extend between top and bottom faces 2 and 3 and between first andsecond side wall faces 6, 7. Side wall faces 6 and 7 are thus of acompound shape and define side voids 11 and 12 between body and headportions 8 and 9 either side of neck portion 10 as a result of thereduced width of neck portion 10 compared to that of body and headportions 8 and 9.

Opening 13 extends through neck portion 10 from top face 2 to bottomface 3. Opening 13 divides neck portion 10 into first and second neckwall members 14 and 15 which extend rearwardly from body portion 8 tohead portion 9. Opening 13 and side voids 11 and 12 reduce the weight ofblock 1, facilitating handling thereof.

The opening may be provided with ledge 37 toward top face 2 covering theforward portion of opening 13, however ledge 37 is dispensed with in analternate embodiment of the block 1′ depicted in FIGS. 6 and 7, leavingthe opening 13′ of constant cross section throughout its depth from thetop face 2′ to the bottom face 3′, further reducing the weight of theblock 1′.

First and second pin holes 16 and 17 are disposed in body portion 8 andopen onto top face 2. Pin holes 16 and 17 are sized to receive pins 50and 51 (discussed below) with a free end of the pin protruding beyondtop face 2. Pin holes 16 and 17 will also typically extend through tobottom face 3 as a result of the preferred method of manufacturediscussed below. First and second pin receiving cavities 18 and 19 aredisposed in body portion 8 and open onto bottom face 3. Pin receivingcavities 18 and 19 receive the free ends of pins protruding from pinholes of vertically adjacent blocks disposed therebeneath in the nextuppermost course so as to interlock the blocks with a predeterminedsetback in the same general manner as that described in the earlierForsberg patent, U.S. Pat. No. Re. 34,134. First and second pin holes 16and 17 (or more preferably additional third and fourth pin holes 29 and30 discussed below) may be positioned such that the predeterminedsetback is zero.

Neck wall members 14 and 15, pin holes 16 and 17 and pin receivingcavities 18 and 19 are positioned such that a first plane P1 extendingparallel to plane of symmetry S passes through first pin receivingcavity 18, first pin hole 16 and first neck wall member 14 and such thatsecond plane P2 extending parallel to plane of symmetry S passes throughsecond pin receiving cavity 19, second pin hole 17 and second neck wallmember 15.

The effect of this configuration is best described with reference toFIG. 5 which depicts first block 1A interlocked with second and thirdblocks 1B, 1C disposed beneath block 1A and laid in a running bondpattern with first block 1A set back from second and third blocks 1B,1C. Pins 50 are received in second pin receiving hole 17B of the secondblock 1B and first pin receiving hole 16C of third block 1C andrespectively engage first and second pin receiving cavities 18A and 19Aof first block 1A so as to provide the interlock between the blocks withthe predetermined setback. As can be seen, the configuration ensuresthat the neck wall members of adjacent blocks overlap. First neck wallmember 14A of first block 1A overlaps second neck wall member 15B ofsecond block 1B, while second neck wall member 15B of first block 1Aoverlaps first neck wall member 14C of third block 1C. This overlapprovides continuity of structure in the neck region between courses ofblocks enabling transfer of compressive loads in this area throughsuccessive courses of blocks, minimizing the bridging of unsupportedareas. Structural integrity of the wall can hence be achieved with alighter mass block with increased opening 13 and void areas 11 and 12,as an increased proportion of the material of the block is able totransfer load between blocks.

The configuration also provides overlap between opening 13A of firstblock 1A and side voids 12B, 11C of second and third blocks 1B, 1C, aswell as between the side voids of first block 1A and openings 13B and13C of second and third blocks 1B, 1C. This overlap provide continuouscavities 38 in the wall which extends through successive courses ofblocks, improving the ease with which the cavities can be filled withcore fill material such as crushed rock to encourage drainage and addstabilizing mass to the wall or alternatively easing placement of grout.Continuous cavities 38 also allow for the placement of guardrail postsor fences at the top of a wall as described below, or for thereinforcement of the wall with rebar and concrete grout as is alsodiscussed below.

Beyond merely overlapping, it is preferred that first and second neckwall members 14 and 15 are positioned so that they will substantiallyvertically align with the neck wall members of blocks in adjacentcourses when laid in a running bond pattern, as is the case with thecurrent preferred embodiment. Such vertical alignment maximizes theresistance of the blocks against crushing when used in extremely tallwalls. This will best be achieved if first and second planes P1 and P2run along or close to planes N1 and N2 running generally centrallythough first and second neck wall members 14 and 15, respectively. Toprovide such vertical alignment and to ensure blocks disposed side byside in a given course of blocks are closely adjacent without anysignificant gap between them, first and second planes P1 and P2 willtypically be located approximately midway between plane of symmetry Sand laterally outermost points 20 and 21 of first and second side wallfaces 6 and 7, respectively.

In the depicted preferred embodiment, as best seen from FIG. 1, planeN1, N2 running generally centrally through each of neck wall members 14,15 lies midway between plane of symmetry S and laterally outermostpoints 20 and 21, while first and second planes P1 and P2 lie slightlyoutboard of planes N1 and N2, a distance equal to 1.5-2% of the overallwidth of the block. This can also be seen in FIG. 5 where the centralplanes (not marked) of the overlapping neck wall members align,resulting in the pin holes of adjacent blocks being slightly offset. Theneck wall members need not extend parallel to plane of symmetry S so asto provide symmetry about planes N1 and N2, so long as planes P1 and P2extend along the length of the neck wall members 14 and 15 so as toprovide continuous support between vertically adjacent blocks.

First and second pin receiving cavities 18 and 19 each have rear wall 22and 23, respectively, which extends generally perpendicularly to planeof symmetry S, allowing for some forgiveness in the positioning ofblocks with respect to vertically adjacent blocks, allowing the blocksto move slightly out of the bond pattern as a result of corners orcurves. Here pin receiving cavity rear walls 22 and 23 are approximately100 mm (4 inches) long. When first block 1A of FIG. 5 is placed with itspin receiving cavities 18A and 19A over pins 50 protruding from pinholes 17B and 16C of second and third blocks 1B and 1C, first block 1Ais manually pushed forward until pins 50 engage pin receiving cavityrear walls 22 and 23, thus interlocking the blocks. The generallytriangular shape of the pin receiving cavities allows minor lateraladjustments of the blocks while maximizing the distance between thefront edge of the cavity and the front face of the blocks which reducesthe possibility of face cracks. The interlocked position defines theset-back between courses of blocks, and is equal to the distance betweenthe pin receiving cavity rear walls 22 and 23 and the rear edge of pinreceiving holes 16 and 17, assuming a constant cross-section pin 50 isemployed. This setback distance can thus be predetermined through thedesign of the block, and will typically be of the order of 25 mm (1inch) for a block such as that depicted which has a height of 200 mm(7.9 inches), providing for a setback of approximately 12.5% or 1:8. Forgiven situations however, it may be desired to design the block for alarger setback, a reduced setback or a zero setback.

Pin receiving cavities 18 and 19 are here approximately 30 mm deep forreception of a pin free end, which will typically project from top face4 of the underlying block by approximately 20 mm. The outer front walls24, 25 of the triangular shaped pin receiving cavities 18 and 19 liegenerally parallel to the outer rearwardly angled surfaces 26 and 27 offront face 4, and spaced approximately 38 mm (1.5 inches) therefrom soas to reduce the possibility of face cracking when forming the roughfront face 4 with the conventional face splitting technique.

The front face is formed of angled outer surfaces 26 and 27 and centralsurface 28 disposed perpendicular to plane of symmetry S so as toprovide for a multi-faceted front face on a wall constructed of theblocks. Alternatively, a variety of front face designs may be used.

Referring to FIGS. 1 to 4, the preferred block has a pair of third andfourth pin holes 29 and 30 disposed forwardly of first and second pinholes 16 and 17 to provide a reduced setback as compared to thatprovided by first and second pin holes 16 and 17. Here that reducedsetback is a zero setback when used with constant cross-section pins 50.Third and fourth pin holes 29 and 30 are each disposed in body portion 8and open onto top face 2 for receiving pin 50 with a free end thereofprotruding beyond top face 2 in a similar manner to first and second pinholes 16 and 17. Third and fourth pin holes 29 and 30 are again disposedon first and second planes P1 and P2, each with their rear edge alignedwith the corresponding pin receiving cavity rear wall 22 and 23 so as toprovide zero setback when used with constant cross-section pins 50.Further pin holes can be provided, if desired, so as to provide forfurther choices of predetermined setback.

Straight retaining wall 100 constructed from the blocks utilizing thirdand fourth pin holes 29 and 30 to interlock the blocks is depicted inFIGS. 8 and 9. As can be seen, use of third and fourth pin holes 29 and30, with a constant cross-section pin 50, provides zero or near verticalsetback between courses resulting in a vertical wall 100. Half blocks 60may be used at the lateral ends of wall 100 in alternate courses tofinish the wall in the usual manner if the wall end abuts a verticalsurface. Half blocks may be field cut using a masonry saw or cut at thefactory. FIG. 9 clearly depicts how alignment of the neck wall membersof vertically adjacent blocks and consequent alignment of neck openings13 with side voids 11 and 12 of vertically adjacent blocks providescontinuous cavities 38 extending through the height of wall 100. Gappingblocks are typically used to finish the top of the wall.

Rather than using a constant-cross section pin 50, an alternate andpreferred collared pin 51, as depicted in FIG. 10, has been developedfor use with current block 1. Lower section 52 of pin 51 is sized to fitinto any of pin holes 16 and 17, 29 or 30, here having a diameter of12.7 mm (0.5 inches). Upper section 53 is of greater cross section thanlower section 52 (and the pin holes), here having a diameter of 18 mm(0.72 inches) so as to form collar 54 at the intersection between upperand lower sections 52, 53. In use, lower section 52 of pin 51 isreceived in pin hole 16,17, 29 or 30, with collar 54 engaging top face 4of block 1 preventing pin 51 from falling through the pin hole andensuring upper section 53 forms a free end protruding a fixed amount(here 20 mm) from the pin hole for engaging a pin receiving cavity of anadjacent block laid in the next course. Pin 51 hence need not extendthrough the entire length of the pin holes to rest on the block beneathor be jammed into the pin hole with an interference fit to hold it inposition.

As well as ensuring the location of pin 51 in the pin hole, theincreased diameter upper section 53 increases the setback betweenadjacent interlocked blocks by the width of the collar, here beingapproximately 2.6 mm. Use of collared pin 51 in third and fourth pinholes 29 and 30 will hence provide a minimal setback between courses ofabout 2.6 mm (or 1.3% for the current block) rather than zero setback aswill be provided with a constant cross-section pin 50. A wallconstructed in this way will still appear essentially vertical but willhave increased stability owing to the setback, albeit only a minorsetback. The collared pin design and the relative position of the pinholes with respect to the pin receiving cavities can be adjusted in thedesign to provide near vertical walls or other desired setbacks.

Block 1 of the preferred embodiment is suitable for forming straight,curved or serpentine walls. To provide for convex faced curved walls andserpentine walls, side wall faces 6 and 7 generally taper from frontface 4 to rear face 5, such that the block is wider at front face 4between outermost points 20 and 21 than at rear face 5. This enables theblocks to be placed in a convex curve in the usual manner withoutinterference between the head portion 9 of laterally adjacent blocks. Toprovide for increased curvature of a convex-curved section of wall, headportion 9 is provided with first and second ears 31 and 32 extendinglaterally beyond first and second neck wall members 14 and 15,respectively. First and second ears 31 and 32 can be knocked off headportion 9 with a bolster or similar as a result of the notches 33 and 34forming weak points in rear face 5 at ears 31 and 32. FIG. 11 depictstwo blocks 1D and 1E of a course with ears 31 and 32 bolstered off andlaid in a tight convex curve. FIG. 11 also shows that body side wallsurfaces 35 and 36 are tapered at an angle sufficient to make full useof the reduced width of head portion 9 when ears 31 and 32 have beenbolstered off without creating any gaps between front faces 4 oflaterally adjacent blocks. FIG. 12 depicts how third block 1 F laid inthe next setback course interlocks with first two blocks 1D and 1E. Thetight convex curve results in pins 50 protruding from the first andsecond pin holes of lower blocks 1D and 1E engage rear walls 22F and 23Fof pin receiving cavities 18F and 19F toward the inner ends thereof.When forming a concave curve, the pins would engage rear walls 22F and23F of pin receiving cavities 18F and 19F toward the outer ends thereof.

A retaining wall formed of courses of blocks of the preferred embodimentcan be reinforced with the use of rebar and grout. An example of suchreinforced wall 200 is depicted in FIG. 13. Lengths of rebar 90 areinserted into at least one of the continuous cavities 38 defined by neckopenings 13 and vertically adjacent side voids 11 and 12 of blocks inalternate courses. Cavities 38 are then filled with grout 91 to encaserebar 90. This form of reinforcing is particularly applicable tovertical or minimum setback walls with blocks interlocked using thirdand fourth pin holes 29 and 30, but can also be used for larger setbackwalls, where cavities 38 defined in the wall will still be continuousbut will be inclined at an angle equal to the setback angle of the wall.Alternatively, the wall may be reinforced by placing threaded rodsthrough the cavities and using conventional post-tension techniques.

The retaining wall can alternatively be reinforced with the use of areinforcing geogrid tie-back in a similar manner to that disclosed inForsberg, U.S. Pat. No. Re. 34,134. Vertical retaining wall 300depicting the use of such a tie-back 92 is shown in FIG. 14. Tie-back 92is a generally flat sheet of material arranged as a grid, typicallyformed of high strength plastics material or steel, which is placedbetween courses of blocks 1 in the retaining wall and extends rearwardlyinto the fill behind wall 300 to anchor the wall against forces tendingto topple the wall forward. Pins 50 interlocking the blocks of adjacentcourses are passed through apertures of tie-back grid 92 so as to assistfixing of tie-back 92 between the courses. The configuration of thepreferred block which ensures neck wall members 14 and 15 of interlockedblocks overlap in line with pins 50 helps resist pull-out of thetie-back reinforcement 92.

FIGS. 14 and 15 also depict the integration of fence posts 93 into thetop of retaining wall 300. Posts 93 of fence 94, or of similarstructures such as guardrails, can be inserted into cavities 38 formedby neck openings 13 and side voids 11 and 12 of the blocks of alternatecourses and secured if necessary with grout 91 or other fill. A singlesign post could also be secured to the wall in such a manner. Due to therelatively short embedment depth of the preferred embodiment,reinforcement of the structure is typically necessary when placing fenceposts 93 in cavities 38. FIGS. 14 and 15 depict geogrid reinforcementfor this purpose.

The shape of preferred block 1 incorporating head, neck and bodyportions 9, 7 and 8 also enables the construction of a retaining wallincorporating pilasters for aesthetic or other purposes. FIG. 16 depictssuch retaining wall 400 incorporating pilaster 95 formed of a verticalcolumn of blocks 1 set forward from the remainder of vertical retainingwall 400. In every second course (here the bottom, middle and topcourses) ears 31 and 32 of the blocks of the pilaster 95 are disposed inside voids 11 and 12 of the laterally adjacent blocks. Preferably,shoulders 39 and 40 of body portion 8 of these blocks engage the outerside surfaces 26 and 27 of front face 4 of the laterally adjacentblocks. In the alternate courses it is preferable to provide truncatedblocks 70 laterally adjacent to the pilaster blocks, these truncatedblocks being used to fill the gaps which would otherwise be formed inthe front face of the wall. The truncated blocks can be formed bycutting half blocks 60 to reduce their width as required. The blocks ofpilaster 95 are interlocked in vertical alignment with pins in third andfourth pin holes 29 and 30 of a given block engaging first and secondpin receiving cavities 28 and 19 respectively of the block immediatelyabove. Alternatively, if constant cross-section pins or rods (whichwould extend through multiple blocks) are used, it would be possible tointerlock the blocks of pilaster 95 using first and second pin holes 16and 17 with the pins protruding into first and second pin holes 16 and17 of the next lowermost block rather than the pin receiving cavities.Setback walls with incorporation of a sloping pilaster can also readilybe achieved in a similar manner, with pins in first and second pin holes16 and 17 of each pilaster block engaging pin receiving cavities 18 and19 of the next lowermost block in the pilaster.

Blocks 1 are typically manufactured of concrete and cast in a high-speedmasonry block or paver machine. The block is formed inverted to allowfor forming of the pin receiving cavities 18 and 19. Pin receivingcavities 18 and 19, neck opening 13 and pin holes 16, 17, 19 and 30 areformed using cores. The pin holes extend through the depth of the blockto enable the pin-hole forming cores to extend to the top face (whichforms the bottom surface during casting). The pin receiving cavitiesextend only through a portion of the depth of the block to enable thepin receiving cavity forming cores to extend from the bottom face (whichis the top surface during casting). Blocks 1 are formed as mirror imagepairs joined at the front face 4 which are then subsequently split usinga standard block splitter in the usual way to provide a rough front face4 on the split blocks 1. Alternatively, other methods may be utilized toform a variety of front face surface appearances. Such methods are wellknown in the art.

Although particular embodiments have been disclosed herein in detail,this has been done for purposes of illustration only, and is notintended to be limiting with respect to the scope of the appendedclaims, which follow. In particular, it is contemplated by the inventorthat various substitutions, alterations, and modifications may be madeto the invention without departing from the spirit and scope of theinvention as defined by the claims. For instance, the choice ofmaterials or variations in the shape or angles at which some of thesurfaces intersect are believed to be a matter of routine for a personof ordinary skill in the art with knowledge of the embodiments disclosedherein.

1. A retaining wall block having parallel top and bottom faces, a frontface, a rear face, first and second side wall faces and a vertical planeof symmetry extending between the front and rear faces, the blockcomprising: a body portion including the front face; a head portionincluding the rear face; a neck portion connecting the body portion andthe head portion, the body, head and neck portions each extendingbetween the top and bottom faces and between the first and second sidewall faces; an opening extending through the neck portion from the topface to the bottom face, the opening dividing the neck portion intofirst and second neck wall members extending rearwardly from the bodyportion to the head portion; first and second pin holes each disposed inthe body portion and opening onto the top face, the first and second pinholes being configured for receiving a pin with a free end of the pinprotruding beyond the top face; and first and second pin receivingcavities each disposed in the body portion and opening onto the bottomface, the first and second pin receiving cavities being configured forreceiving the free end of a pin received in a pin hole of an adjacentblock disposed therebeneath so as to interlock the blocks with apredetermined setback; wherein the pin receiving cavities are positionedin the body portion such that a first vertical plane extending centrallythrough the first neck wall member intersects the first pin receivingcavity and a second vertical plane extending centrally through thesecond neck wall member intersects the second pin receiving cavity. 2.The retaining wall block of claim 1 wherein the first and second pinreceiving cavities each have a rear wall extending generallyperpendicularly to the plane of symmetry.
 3. The retaining wall block ofclaim 1 wherein the block further comprises third and fourth pin holeseach disposed in the body portion and opening onto the top face, thethird and fourth pin holes being configured for receiving a pin with afree end of the pin protruding beyond the top face, the third and fourthpin holes being disposed on the first and second planes forward of thefirst and second pin holes so as to provide a reduced or zeropredetermined setback.
 4. The retaining wall block of claim 1 whereinthe side wall faces generally taper from the front face to the rearface.
 5. The retaining wall block of claim 1 wherein the head portionhas first and second ears extending laterally beyond the first andsecond neck wall members, respectively, the first and second ears eachbeing provided with a notch to enable the ears to be knocked off thehead portion.
 6. The retaining wall block of claim 1 wherein the firstand second planes are parallel to the vertical plane of symmetry.
 7. Theretaining wall block of claim 1 wherein the first plane intersects thefirst pin hole and the second plane intersects the second pin hole.